The U.J. is the abbreviation for Univeral Joint tool (also know as a ratchet swivel flex universal joint extension).
This jpeg shows this tool attached to a rachet, the extension bars, the swivel, and the socket all assembled to give access the upper mounting bolt of the starter. Also a close-up of the swivel flex universal joint extension.
Here is information from the JTIS:
Remove the starter motor securing bolts.Remove the upper securing bolt. Preferably, use a short 13 mm spanner or a Snap On Half Moon spanner CMX1113 to initially loosen the bolt.
The upper bolt may be removed (after loosening) using a 3/8' square drive 13 mm socket, extensions and U.J as shown.
I think to 300 length is 300 mm or about 11 inches, and the 140 is 140 mm or about 5 1/2 inches.
Hope this helps